Alkali stress cracking resistant polycarbonate alloy material and preparation method thereof

Abstract

The invention discloses an alkali stress cracking resistant polycarbonate alloy material and a preparation method of the alkali stress cracking resistant polycarbonate alloy material, and belongs to the technical field of high polymer materials. Comprising the following components in percentage by weight: 20-60% of polycarbonate, 25-40% of polyester, 10-30% of a core-shell copolymer, 2-10% of an acrylate copolymer, 0.1-0.5% of an antioxidant and 0.1-0.5% of a lubricant, and the polyester and the core-shell copolymer are added into the polycarbonate to block erosion of alkaline substances to the polycarbonate, so that the alkali resistance of the material is improved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a polycarbonate alloy material resistant to alkali stress cracking and its preparation method. Background Technology

[0002] Polycarbonate, a high-molecular polymer containing carbonate groups in its molecular chain, occupies an important position in the field of modern materials. It is renowned for its high strength, transparency, and impact resistance. Its good transparency and superior ductility and toughness make it suitable as a transparent decorative material. With continuous technological advancements, polycarbonate has been widely used in various environments such as home furnishings, smart appliances, and smart kitchens and bathrooms, bringing great convenience and aesthetics to people's lives and driving the development of related industries in terms of product design and performance improvement.

[0003] In existing technologies for solving application problems related to polycarbonate, conventional methods are typically employed. For example, to improve certain properties of the material, special coatings are applied to the surface. By coating the polycarbonate surface with a layer of specific function, properties such as stain resistance and abrasion resistance are improved. Chemical modification of the polycarbonate molecular structure is also performed, by introducing other chemical groups or altering the arrangement of molecular chains, with the aim of obtaining better physical and chemical properties. Furthermore, optimizing processing techniques, such as adjusting molding temperature and pressure parameters, is used to improve the quality and performance of polycarbonate products, enabling them to better adapt to different usage environments.

[0004] However, existing technologies have significant drawbacks. Current conventional methods cannot effectively address the issue of polycarbonate's susceptibility to corrosion from certain washing solutions during use, which can easily lead to environmental stress cracking. This severely impacts the application of polycarbonate in demanding fields, limiting its service life and scope of use. Summary of the Invention

[0005] To address the problems in the prior art, this invention provides a polycarbonate alloy material resistant to alkali stress cracking and its preparation method. This application improves the alkali resistance of the material by adding polyester and core-shell copolymer to polycarbonate to block the erosion of polycarbonate by alkaline substances.

[0006] The first aspect of this invention provides a polycarbonate alloy material resistant to alkali stress cracking, employing the following technical solution: A polycarbonate alloy material resistant to alkali stress cracking comprises the following components in weight percentage: 20-60% polycarbonate, 25-40% polyester, 10-30% core-shell copolymer, 2-10% acrylate copolymer, 0.1-0.5% antioxidant, and 0.1-0.5% lubricant.

[0007] In a preferred embodiment, the core-shell copolymer is a butyl acrylate-methacrylate copolymer with epoxy functional groups.

[0008] By employing the above technical solutions, polycarbonate itself possesses high strength, transparency, impact resistance, good transparency, and superior ductility and toughness, but it is susceptible to environmental stress cracking due to erosion by washing solutions. Adding polyester, with its stable chemical structure, allows it to form a good blend system with polycarbonate, acting as a reinforcing skeleton in the alloy material, blocking the erosion of polycarbonate by alkaline substances, thereby improving the material's alkali resistance. Core-shell copolymers have a special core-shell structure; the epoxy functional groups of their outer shell can chemically react with the molecular chains of polycarbonate and polyester to form chemical bonds, enhancing intermolecular bonding and compatibility, making the material structure denser. This reduces the channels for alkaline substances to enter the material's interior, improving alkali resistance; furthermore, it better disperses stress under external forces, improving crack resistance. Acrylic copolymers possess good flexibility and compatibility, and can be uniformly dispersed in the polycarbonate and polyester matrix, improving the material's interfacial properties, further enhancing the overall bonding strength and stability, effectively resisting the erosion of alkaline substances and external impacts, and improving alkali resistance and crack resistance. Antioxidants prevent materials from being oxidized during processing and use, while lubricants reduce frictional resistance during processing, making the material easier to form and ensuring stable performance. Together, these factors improve the alkali stress cracking resistance of polycarbonate alloys, thereby increasing the service life and application range of polycarbonate.

[0009] In a preferred embodiment, the core-shell copolymer is obtained by the following preparation method: S1. A core solution is obtained by mixing butyl acrylate, crosslinking agent, initiator, dispersant and water; S2. Add a shell monomer and initiator solution composed of methyl methacrylate and glycidyl acrylate dropwise to the core solution. After the addition is completed, keep the reaction at a constant temperature to obtain a core-shell structure emulsion of butyl acrylate-methyl methacrylate copolymer with epoxy functional groups. The emulsion is then frozen, thawed to break the emulsion, washed, filtered and dried to obtain a core-shell copolymer.

[0010] In a preferred embodiment, the preparation of the core solution in step S1 is as follows: first, butyl acrylate is mixed with a crosslinking agent, an initiator, a dispersant and water, and then reacted at 65-70°C for 30-35 minutes. The total amount of butyl acrylate and crosslinking agent accounts for 5% of the total amount of core-shell monomers. Then, a mixture of butyl acrylate and allyl methacrylate, accounting for 70% of the total amount of core-shell monomers, is added. After adding an initiator and reacting for 1-1.5 hours, the core solution is obtained.

[0011] By adopting the above technical solution, the core solution of the core-shell copolymer in polycarbonate alloy material is prepared in a specific manner. First, a portion of butyl acrylate is mixed with a crosslinking agent and reacted at a specific temperature and time. Then, a mixture of butyl acrylate and allyl methacrylate is added to continue the reaction, making the core-shell copolymer structure more stable. The specific proportions of butyl acrylate, the mixture of butyl acrylate and allyl methacrylate, and the appropriate proportions of the subsequent shell monomers methyl methacrylate and glycidyl acrylate help to improve the stability and compatibility of the core-shell copolymer, thereby improving the alkali stress cracking resistance of the polycarbonate alloy material and increasing its service life and application range.

[0012] In a preferred embodiment, the mass ratio of butyl acrylate to allyl methacrylate in the mixture is (3-6):1.

[0013] In a preferred embodiment, the crosslinking agent is 1,4-butanediol diacrylate.

[0014] In a preferred embodiment, the mass ratio of methyl methacrylate to glycidyl acrylate is (30-35):1.

[0015] In a preferred embodiment, the polyester is polybutylene terephthalate.

[0016] In a preferred embodiment, the acrylate copolymer is a styrene-acrylate copolymer.

[0017] A second aspect of the present invention is to provide a method for preparing a polycarbonate alloy material resistant to alkali stress cracking as described above, comprising the following steps: Polycarbonate, polyester, core-shell copolymer, acrylate copolymer, antioxidant, and lubricant are mixed evenly and then extruded in a twin-screw extruder to obtain polycarbonate alloy material.

[0018] In summary, the present invention has the following beneficial effects: The synergistic effect of polyester, core-shell copolymer, acrylate copolymer, and polycarbonate in this application effectively improves the alkali resistance of the polycarbonate alloy material. Furthermore, the mutual coordination between the components results in a more compact material structure, reducing the penetration of alkaline substances into the material's interior while also effectively improving the polycarbonate alloy material's crack resistance. Therefore, the polycarbonate alloy material obtained in this application can be widely used in the housings of instruments in smart homes, smart kitchens and bathrooms, new energy vehicles, and electronic communications, demonstrating its broad application scope. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to the embodiments. All reagents, unless otherwise specified, are commercially available conventional reagent products.

[0020] Preparation Example 1 A method for preparing butyl acrylate-methacrylate copolymers with epoxy functional groups includes the following steps: S1. Add 3g of sodium dodecyl sulfate to 1400g of water and stir to disperse evenly. Then add 50g of butyl acrylate and 0.54g of 1,4-butanediol diacrylate. Next, add 25% of the total amount of potassium persulfate and react at 65℃ for 30 min. The total amount of potassium persulfate is 1% of the total amount of the core-shell monomer. The potassium persulfate is added in the form of an aqueous solution. The addition methods in other steps are the same. S2. Add 707.56 g of a mixture of butyl acrylate and allyl methacrylate, which accounts for 70% of the total core-shell monomers, dropwise to step S1, while simultaneously adding 50% of the total potassium persulfate. The monomer mixture and potassium persulfate aqueous solution are added dropwise over 2 hours. After the addition is completed, react at 65°C for 1.5 hours to obtain the core solution; wherein the mass ratio of butyl acrylate to allyl methacrylate is 3:1. S3. Add 252.7g of shell monomer (25% of the total core-shell monomers) composed of methyl methacrylate and glycidyl acrylate and the remaining potassium persulfate solution dropwise to the core solution. After the addition is completed, keep the reaction at the temperature for 2 hours to obtain a core-shell structured emulsion. The emulsion is then frozen, thawed to break the emulsion, washed, filtered and dried to obtain a core-shell copolymer, wherein the mass ratio of methyl methacrylate to glycidyl acrylate is 30:1.

[0021] Preparation Example 2 A method for preparing butyl acrylate-methacrylate copolymers with epoxy functional groups includes the following steps: S1. Add 3g of sodium dodecyl sulfate to 1400g of water and stir to disperse evenly. Then add 50g of butyl acrylate and 0.54g of 1,4-butanediol diacrylate. Next, add 25% of the total amount of potassium persulfate and react at 70℃ for 35min. The total amount of potassium persulfate is 1% of the total amount of the core-shell monomer. The potassium persulfate is added in the form of an aqueous solution. The addition methods in other steps are the same. S2. Add 707.56 g of a mixture of butyl acrylate and allyl methacrylate, which accounts for 70% of the total core-shell monomers, dropwise to step S1, while simultaneously adding 50% of the total potassium persulfate. The monomer mixture and potassium persulfate aqueous solution are added dropwise over 2 hours. After the addition is completed, react at 70°C for 1 hour to obtain the core solution. The mass ratio of butyl acrylate to allyl methacrylate is 6:1. S3. Add 252.7g of shell monomer (25% of the total core-shell monomers) composed of methyl methacrylate and glycidyl acrylate and the remaining potassium persulfate solution dropwise to the core solution. After the addition is completed, keep the reaction at the temperature for 2 hours to obtain a core-shell structure emulsion. The emulsion is then frozen, thawed to break the emulsion, washed, filtered and dried to obtain a core-shell copolymer, wherein the mass ratio of methyl methacrylate to glycidyl acrylate is 35:1.

[0022] Preparation Example 3 The preparation method of butyl acrylate-methacrylate copolymer differs from that of Preparation Example 1 in that only methyl methacrylate is added in step S3, and glycidyl acrylate is not added. All other steps are the same as those in Preparation Example 1.

[0023] Example 1 A method for preparing a polycarbonate alloy material resistant to alkali stress cracking includes the following preparation steps: 2 kg of polycarbonate, 3.9 kg of polybutylene terephthalate, 3 kg of butyl acrylate-methacrylate copolymer with epoxy functional groups obtained in Preparation Example 1, 1 kg of styrene-acrylate copolymer, 0.05 kg of hindered phenolic antioxidant, and 0.05 kg of pentaerythritol stearate lubricant were mixed evenly and then extruded in a twin-screw extruder. After water cooling and forced air drying, the mixture was granulated to obtain polycarbonate alloy material. The temperature of the twin-screw extruder was 220-300℃. The granules were then dried in a blower box, injection molded into standard test strips, and then subjected to performance testing.

[0024] Example 2 A method for preparing a polycarbonate alloy material resistant to alkali stress cracking includes the following preparation steps: 4 kg of polycarbonate, 3.3 kg of polybutylene terephthalate, 2 kg of butyl acrylate-methacrylate copolymer with epoxy functional groups obtained in Preparation Example 1, 6.5 kg of styrene-acrylate copolymer, 0.03 kg of hindered phenolic antioxidant, and 0.02 kg of pentaerythritol stearate lubricant were mixed evenly and then extruded in a twin-screw extruder. After water cooling and forced air drying, the mixture was granulated to obtain polycarbonate alloy material. The temperature of the twin-screw extruder was 220-300℃. The granules were then dried in a blower box, injection molded into standard test strips, and then subjected to performance testing.

[0025] Example 3 A method for preparing a polycarbonate alloy material resistant to alkali stress cracking includes the following preparation steps: 6 kg of polycarbonate, 2.5 kg of polybutylene terephthalate, 1 kg of butyl acrylate-methacrylate copolymer with epoxy functional groups obtained in Preparation Example 1, 4.8 kg of styrene-acrylate copolymer, 0.01 kg of hindered phenolic antioxidant, and 0.01 kg of pentaerythritol stearate lubricant were mixed evenly and then extruded in a twin-screw extruder. After water cooling and forced air drying, the mixture was granulated to obtain a polycarbonate alloy material. The temperature of the twin-screw extruder was 220-300℃. The granules were then dried in a blower box, injection molded into standard test strips, and then subjected to performance testing.

[0026] Example 4 A method for preparing a polycarbonate alloy material resistant to alkali stress cracking includes the following preparation steps: 3.2 kg of polycarbonate, 4 kg of polybutylene terephthalate, 2.5 kg of butyl acrylate-methacrylate copolymer with epoxy functional groups obtained in Preparation Example 1, 2 kg of styrene-acrylate copolymer, 0.05 kg of hindered phenolic antioxidant, and 0.05 kg of pentaerythritol stearate lubricant were stirred and mixed evenly, and then extruded in a twin-screw extruder. After water cooling and forced air drying, the mixture was granulated to obtain polycarbonate alloy material. The temperature of the twin-screw extruder was 220-300℃. The granules were then dried in a blower box, injection molded into standard test strips, and then subjected to performance testing.

[0027] Example 5 A method for preparing a polycarbonate alloy material resistant to alkali stress cracking differs from Example 2 in that the butyl acrylate-methacrylate copolymer with epoxy functional groups is the core-shell copolymer obtained in Preparation Example 2, while all other aspects are the same as in Example 2.

[0028] Comparative Example 1 A method for preparing a polycarbonate alloy material resistant to alkali stress cracking differs from Example 2 in that the core-shell copolymer is the butyl acrylate-methacrylate copolymer obtained in Preparation Example 3, while all other aspects are the same as in Example 2.

[0029] Comparative Example 2 A method for preparing a polycarbonate alloy material resistant to alkali stress cracking differs from Example 2 in that an equal amount of ABS polymer is used instead of butyl acrylate-methacrylate copolymer with epoxy functional groups; otherwise, the method is the same as in Example 2.

[0030] Comparative Example 3 A method for preparing a polycarbonate alloy material resistant to alkali stress cracking differs from Example 2 in that an equal amount of poly(n-butyl acrylate-R-glycidyl methacrylate) random copolymer (Mw = 20w) is used instead of the core-shell butyl acrylate-methacrylate copolymer with epoxy functional groups obtained in Example 1. All other aspects are the same as in Example 2.

[0031] Performance testing The tensile properties, notched impact strength, and alkali stress cracking resistance of the polycarbonate alloy materials obtained in the above embodiments and comparative examples were tested, and the test results are shown in Table 1.

[0032] Tensile properties were tested according to ISO 527 method, with a tensile speed of 50 mm / min; Notched impact strength was tested according to ISO 179 / leA method, with a 4 mm thick test using a simply supported beam notched impact method.

[0033] The test method for evaluating alkali stress cracking resistance is to soak the sample in a 5 wt% sodium hydroxide solution for 6 hours, followed by a tensile strip torsion test, and the excellent performance of stress cracking resistance is judged by the cracking time.

[0034] Table 1. Test Results of Polycarbonate Alloy Materials Based on the test data in Table 1: The polycarbonate alloy materials obtained in Examples 1-5 of this application exhibit good tensile and impact resistance. Furthermore, after immersing the polycarbonate alloy materials obtained in this application in a 5 wt% sodium hydroxide solution for 6 hours, the cracking time of the polycarbonate alloy materials during tensile and torsional tests was consistently above 25 minutes. This indicates that the polycarbonate alloy materials obtained in this application can not only effectively resist the corrosion of alkaline substances, but also enhance the intermolecular bonding force through the chemical reaction between the core-shell copolymer butyl acrylate-methacrylate copolymer with epoxy functional groups and polycarbonate and polybutylene terephthalate. This results in the polycarbonate alloy materials obtained in this application exhibiting excellent impact resistance. Additionally, under alkaline corrosion, the tensile and torsional tests show better stress dispersion, improving the alkali stress cracking resistance of the polycarbonate alloy materials.

[0035] Compared with Example 2, when using butyl acrylate-methacrylate copolymer without epoxy groups, the tensile properties, notched impact strength, and alkali cracking time of the polycarbonate alloy are reduced. This is because the butyl acrylate-methacrylate copolymer is only bonded to polycarbonate and polyester by intermolecular forces. This weak interfacial bond cannot effectively transfer stress. Therefore, when subjected to external force, the impact energy cannot be effectively absorbed by the rubber particles, which will lead to cracking. Furthermore, due to the weak interfacial bond, alkaline substances can penetrate into the alloy material more quickly, leading to environmental stress cracking.

[0036] Compared with Example 2, when ABS polymer was used instead of butyl acrylate-methacrylate copolymer with epoxy functional groups, the tensile strength, notched impact strength, and alkali cracking time all decreased significantly. This may be because ABS polymer and polycarbonate lack reactive functional groups and rely mainly on intermolecular forces for compatibility, resulting in weak interfacial adhesion. Furthermore, the low-strength rubber phase and brittle styrene-acrylonitrile can become internal defects, which are more likely to become stress concentration points under tensile stress and lead to premature failure. This results in a significant decrease in the overall tensile strength, impact strength, and alkali cracking time of the alloy. In contrast, butyl acrylate-methacrylate copolymer with epoxy functional groups can chemically react with polycarbonate and polyester to form a strong covalent bond interface. This interfacial adhesion can effectively transfer stress, thus significantly improving both notched impact strength and alkali cracking time.

[0037] Compared to Example 2, when a random copolymer of poly(n-butyl acrylate-R-glycidyl methacrylate) was used instead of the core-shell butyl acrylate-methacrylate copolymer with epoxy functional groups, the tensile properties of the polycarbonate alloy material were basically the same as in Example 2. The random copolymer of poly(n-butyl acrylate-R-glycidyl methacrylate), as an excellent reactive compatibilizer, can improve interfacial adhesion through a reaction between epoxy groups and polycarbonate and polyester, thus helping to maintain good tensile strength by keeping stress at the bottom of the phase bed. However, the notched punch of polycarbonate... Impact strength and alkali cracking time will be significantly reduced because core-shell copolymers not only optimize interfacial adhesion, but their rubber core can also absorb impact energy, passivate crack tips, and prevent crack propagation, thereby delaying the penetration of alkaline substances. Therefore, core-shell copolymers achieve ultra-high performance through the division of labor and cooperation between the rubber core and the reaction shell. In contrast, random copolymers simply bind the components tightly and disperse them uniformly to form a stable and homogeneous structure. Although good interfacial energy can delay alkali erosion, once microcracks are generated, they will propagate more easily, resulting in a significant reduction in environmental stress cracking resistance.

[0038] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A polycarbonate alloy material resistant to alkali stress cracking, characterized in that: It includes the following components by weight percentage: 20-60% polycarbonate, 25-40% polyester, 10-30% core-shell copolymer, 2-10% acrylate copolymer, 0.1-0.5% antioxidant, and 0.1-0.5% lubricant.

2. The polycarbonate alloy material resistant to alkali stress cracking according to claim 1, characterized in that: The core-shell copolymer is a butyl acrylate-methacrylate copolymer with epoxy functional groups.

3. The polycarbonate alloy material resistant to alkali stress cracking according to claim 2, characterized in that: The core-shell copolymer was obtained using the following preparation method: S1. A core solution is obtained by mixing butyl acrylate, crosslinking agent, initiator, dispersant and water; S2. Add a shell monomer and initiator solution composed of methyl methacrylate and glycidyl acrylate dropwise to the core solution. After the addition is completed, keep the reaction at a constant temperature to obtain a core-shell structure emulsion of butyl acrylate-methyl methacrylate copolymer with epoxy functional groups. The emulsion is then frozen, thawed to break the emulsion, washed, filtered and dried to obtain a core-shell copolymer.

4. The polycarbonate alloy material resistant to alkali stress cracking according to claim 3, characterized in that: The preparation of the core solution in step S1 is as follows: first, butyl acrylate is mixed with crosslinking agent, initiator, dispersant and water and reacted at 65-70℃ for 30-35 min. The total amount of butyl acrylate and crosslinking agent accounts for 5% of the total amount of core and shell monomers. Then, a mixture of butyl acrylate and allyl methacrylate, accounting for 70% of the total amount of core and shell monomers, is added. After adding the initiator and reacting for 1-1.5 h, the core solution is obtained.

5. A polycarbonate alloy material resistant to alkali stress cracking according to claim 3, characterized in that: In the mixture of butyl acrylate and allyl methacrylate, the mass ratio of butyl acrylate to allyl methacrylate is (3-6):

1.

6. The polycarbonate alloy material resistant to alkali stress cracking according to claim 3, characterized in that: The crosslinking agent is 1,4-butanediol diacrylate.

7. A polycarbonate alloy material resistant to alkali stress cracking according to claim 3, characterized in that: The mass ratio of methyl methacrylate to glycidyl acrylate is (30-35):

1.

8. The polycarbonate alloy material resistant to alkali stress cracking and its preparation method according to claim 1, characterized in that: The polyester used is polybutylene terephthalate.

9. The polycarbonate alloy material resistant to alkali stress cracking and its preparation method according to claim 1, characterized in that: The acrylate copolymer is a styrene-acrylate copolymer.

10. A method for preparing a polycarbonate alloy material resistant to alkali stress cracking as described in any one of claims 1-9, characterized in that: Includes the following steps: Polycarbonate, polyester, core-shell copolymer, acrylate copolymer, antioxidant, and lubricant are mixed evenly and then extruded in a twin-screw extruder to obtain polycarbonate alloy material.

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